Linaria Canadensis Research Articles

Application of field study on Linaria canadensis (L.) Dum. Cours., a naturalized plant of Japan, to science classes in junior high school

Application of field study on <i>Linaria canadensis</i> (L.) Dum. Cours., a naturalized plant of Japan, to science classes in junior high school

Limitations of stable carbon isotope analysis for determining natal host origins of tobacco budworm, Heliothis virescens

AbstractDifferences in the stable carbon isotope ratios of plants utilizing the C3 vs. C4 photosynthetic pathway have been used to broadly identify the natal host origins of herbivorous insects. This study explored whether adequate variation exists between the carbon isotope ratios of different C3 plants in the host range of Heliothis virescens (Fabricius) (Lepidoptera: Noctuidae) to enable accurate identification of natal host‐plant species. Isotope ratio mass spectrometry (IRMS) analysis of 13C/12C ratios of moths reared on four crop plant species [Gossypium hirsutum (L.), Nicotiana tabacum L., Glycine max (L.) Merrill, and Arachis hypogaea L.] and two common weed species [Geranium carolinianum L. and Linaria canadensis (L.) Chaz.] revealed a range of δ13C values within that expected for plants utilizing the C3 photosynthetic pathway. Analysis of vegetative and reproductive tissues from the plants utilized in the study resulted in statistically different δ13C values for some plant species; nevertheless, the range of δ13C values observed for many plant species overlapped. Significant differences in mean δ13C values were detected between groups of moths reared on different host‐plant species, but there was no significant correlation between the δ13C values of moths vs. the δ13C value of plant tissue on which they were reared. Feral tobacco budworm moths collected over 3 years were found to have carbon isotope ratios consistent with those having fed on C3 plants, confirming little utilization of C4 plant species by the insect. Results demonstrate that within the range of C3 host plants tested, carbon isotope signatures are not sufficiently unique to enable a reliable determination of natal origin of feral tobacco budworm with current IRMS technology.

Morphological Constraints on Fruit Size in Linaria canadensis

This article presents the results of an experiment designed to examine the relative importance of plant architecture and resource limitation on offspring traits in the annual Linaria canadensis. We compared fruit size and seed number on plants that varied in their degree of resource availability by creating two groups of plants: (1) by removing all developing fruit on inflorescences, plants were free from resource competition, and (2) control plants were unmanipulated and therefore had higher levels of resource competition. The removal treatment did not affect the size of subsequently produced fruit. However, fruit size and seed number per fruit were directly related to the thickness of the stem at a fruit's node. Thus, independent of resource availability, plant architecture (stem thickness) regulates or is associated with critical components of female reproductive success.

CORRIDOR AND DISTANCE EFFECTS ON INTERPATCH MOVEMENTS: A LANDSCAPE EXPERIMENT WITH BUTTERFLIES

The hypothesis that corridors increase animal movement between habitat fragments, a central tenet of conservation biology, has been virtually untested. This study demonstrates that corridors increase interpatch movement rates of two butterfly species. The hypothesis was tested in a large-scale, replicated experiment, in which 27 equal-sized (1.64-ha) patches of early successional habitat were created within large areas of pine forest. Patches varied in whether or not they were connected to another patch by a corridor, and in their distance from other patches (64–384 m). The results of mark–release–recapture studies showed that two open-habitat butterfly species, Junonia coenia and Euptoieta claudia, moved more frequently between patches connected by corridors than between unconnected patches. Interpatch movement was significantly, negatively related to interpatch distance. Interpatch movement rates of J. coenia were significantly, positively related to the density of its host and nectar resource, Linaria canadensis. Corridor effects were stronger for males than for females and were most pronounced within three days after butterflies were marked. Pine forest was not a complete barrier to butterfly movement; both species moved between unconnected patches, even at the longest distances. However, the results of this study suggest that corridors will increase long-distance movements of habitat-restricted species.

Polymorphic Floral Traits in Linaria canadensis (Scrophulariaceae)

-This study examined several aspects of a previously unreported flower color polymorphism in the annual plant Linaria canadensis. Natural populations in southeastern Georgia contained mainly two petal color morphs: the 'dark' purple morph and the 'light' blue morph (two individuals of a completely 'white' albino morph were also found). The frequency of the color morphs varied dramatically among six natural populations. The color morphs were equally common in two populations, in two more populations the dark morph was significantly more abundant than the light morph, and the light morph was more common than the dark morph in two other populations. The two flower color morphs did not differ significantly in number of stems, stem length and number of flowers and fruit. Also, the probability of germination under greenhouse conditions was the same for seeds produced by both flower types. However, flower size was an extremely variable trait (range 624 mm in length) and differed significantly between the morphs; flowers of the light morph were approximately 40% larger than those of the dark morph. Perhaps due to the developmental continuity between flowers and fruits, fruit derived from light-colored flowers were significantly larger than fruit produced by dark-colored flowers. Since fruit size will be correlated with either the size or number of seeds produced, there are likely to be fitness consequences of the flower color polymorphism for the population biology of L. candensis.

Microhabitat du Linaria canadensis (Scrophulariceae) dans le Haut-Saint-Laurent (Québec)

The influence of vegetation structure on the abundance of Linaria canadensis (L.) Dum.-Cours., a rare species in Quebec, has been studied. Six populations from two bogs of extreme southwestern Quebec have been sampled. These populations were located on recently bumed areas and on the fallow margins of cultivated fields. Linear regressions showed two very highly significant relationships: the species density is directly related to the proportion of bare soil and inversely related to moss layer cover. Thus, in the study area, Linaria canadensis appears to be a transient successional species, the presence and abundance of which is closely linked to disturbances such as fire and clearings. The existence of a wide morphocline is also discussed.

Heliothis 1 spp.: Larvae and Associated Parasites and Diseases on Wild Host Plants in the Pee Dee Area of South Carolina 2

In 1972 and 1973, numerous wild host plants in the Pee Dee area of South Carolina were surveyed for populations of larvae of Heliothis spp. Carolina geranium, Geranium carolinianum L., toadflax, Linaria canadensis L., beard-tongue, Penstemon laevigatus Aiton, and crimson clover, Trifolium incarnatum L., were primary spring hosts; later in the season, beggarweed, Desmodium spp., deergrass, Rhexia spp., morning glory, Ipomoea spp., prickly sida, Sida spinosa L., and bicolor lespedeza, Lespedeza bieolor Turcz., were favored. Only the parasities Cardioehiles nigrieepes Viereck and Campoletis spp. and the disease Spiearia rileyi (Farlow) Charles occurred frequently enough to deter the development of populations of Heliothis spp. in the Pee Dee area of South Carolina.

Geranium carolinianum as an Early Host for Heliothis zea and H. virescens (Lepidoptera: Noctuidae) in the Southeastern United States, with Notes on Associated Parasites1

Larvae of Heliothis virescens (F.) and H. zea (Boddie) were collected abundantly during 1964 and 1965 from Carolina cranesbill, Geranium carolinianum L., in Georgia, Mississippi, and South Carolina. This plant was found serving as a previously unreported early-season host throughtout the collection area. Population densities of the respective larvae on it are reported for the various areas, as well as those in a single collection from toadflax, Linaria canadensis (L.) Dumont, adjacent to a South Carolina stand of G. carolinianum . Seven species of hymenopterous parasites, namely, Cardiochiles nigriceps Viereck, Microplitis croceipes (Cresson), Hyposoter sp., Campoletis sp., Rogas aciculatus (Cresson), Apanteles marginiventris (Cresson), and Netelia (Netelia) sp., were identified from the Heliothis of the 1965 collections.